Developmental physiological changes occur throughout childhood, with important changes observed within the first few weeks and months from birth, potentially affecting drug pharmacokinetics. The impact of confounding factors in relation to the availability of clinically relevant and adequate drug formulations and administration devices is underestimated. Hence, it is important to highlight presently the relevance of formulation issues. Since 2007, the EU Paediatric Regulation enforces paediatric investigation plans in which the applicant has to justify the clinical relevance of each dosage form proposed in relation to age subsets involved and the suitability of administration modalities. Therefore, pediatric drug development has become more relevant, and the importance of using age-appropriate drug formulations has been acknowledged by investigators and other stakeholders. Palatability and acceptability assessment is considered to be important by the regulatory bodies as well as excipient safety and tolerability, as it can be an issue particularly in very young children. However, there remains a lack of research into pediatric biopharmaceutics (methodological input regarding in vitro tools and bridging studies). Clinical pharmacologists with expertise ranging from pharmacodynamics, pharmacokinetics, adverse drug effects, and toxicology should actively contribute in advancing drug formulation issues in children.